Radial Compressor

ABSTRACT

A radial compressor for a turbo charger has a housing with an inflow passage and a spiral passage. A compressor wheel is supported rotatably in the housing. The housing has at least two housing parts between which a cavity is formed. At least one opening is provided in the inflow passage, wherein the at least one opening fluidically connects the cavity with the inflow passage.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 USC 119 of foreign application DE 10 2009 051 104.0 filed in Germany on Oct. 28, 2009, and which is hereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

The invention concerns a radial compressor, especially for a turbo charger, comprising a housing with an inflow passage and a spiral passage, wherein in the housing a compressor wheel is rotatably supported. The housing is comprised of at least two housing parts between which at least one cavity is formed.

Turbo engines are generally used in connection with internal combustion engines in order to compress, for the purpose of increasing performance and efficiency, the sucked-in fresh air to a higher pressure level. In case of exhaust gas turbo chargers the housing is comprised of metal because of the high temperatures and high pressures. Moreover, mechanically or electrically driven compressors are known whose housing is comprised of plastic material. When operating the compressor in particular at high engine speeds significant noise is developed that, because of the high frequencies, is perceived as disturbing and unpleasant. On the one hand, these are constant sounds caused by natural dynamic frequencies of the rotating shaft and the oil film. Moreover, there exist numerous noises variable with regard to their frequency spectra that are caused, for example, by shaft imbalances, pulsation phenomena, aerodynamic effects (for example, flow about the compressor or turbine vanes). The frequency range of these problem noises are in general within a very broad bandwidth of approximately 1,000 Hz to 20,000 Hz. These noises are partially introduced as structure-borne sound into the structure and radiate from there outwardly. A further portion of the disturbing noises is emitted directly as airborne sound. This airborne sound propagates along the airborne sound pathways.

In order to dampen the sound that is emitted to the exterior by the turbo charger, in DE 10112764 A1 a radial compressor has been proposed whose housing and pressure-side socket are comprised of plastic material. For noise damping in the area of the spiral housing, acoustically acting openings are provided that are designed as blind bores or are formed as chambers that are separated by a perforated sheet from the flow passage.

DE 202007016282 U1 discloses a housing for a radial compressor that is comprised of three housing parts that are connected to one another at joining or connecting surfaces.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to propose a radial compressor of the aforementioned kind where a significant noise reduction is realized at the housing in a simple way.

In accordance with the present invention, this is achieved in that at the inflow passage at least one opening is provided by means of which the cavity is in fluidic communication with the inflow passage.

The present invention is based on the concept that sound waves that are propagating in the direction of the air intake opening, in addition to noise emission of the air-guiding parts, also negatively affect the outlet noise. This effect is counteracted in that between the housing parts at least one acoustic dampening cavity is provided that by means of at least one opening is connected fluidically to the inflow passage. Since the openings are provided in the intake cross-section of the compressor, acoustic damping possibilities are provided directly at the source of the sound in this way.

According to a preferred embodiment of the invention, the inflow passage is substantially formed by an axial section of a central housing part. Alternatively, the inflow passage may be formed substantially by an axial section of a top housing part and an axial section of the central housing part.

There are various options for designing the openings that connect the inflow passage fluidically with the cavity. One of these design options provides that the opening in the intake passage is formed by a spacing between axial sections of the top housing part and the central housing part. This spacing provides a slot extending in circumferential direction between the axial sections.

Alternative designs reside in that in the axial sections a plurality of openings are provided. These openings can be formed, for example, as slotted holes that extend preferably parallel to one another in axial direction of the inflow passage. It is also possible to design the openings to be of a circular shape or a polygonal shape. A particularly preferred embodiment of the invention resides in that a partition is provided by means of which two or more subcavities are formed. In this way, individual volumes are provided; it is possible that these individual volumes are differently sized or are of the same size. For a multi-part design of the housing it is expedient that the cavity is of an annular design and surrounds the axial section or axial sections.

As a partition, for example, an annular radial partition may be provided that separates an upper subcavity and a lower subcavity, each having an individual volume, from one another. Alternatively, it is also possible to provide axial partitions wherein two or several partitions form a corresponding number of subcavities. In this connection, preferably three axial partitions are provided that surround the axial section(s) and in this way form three ring segment-shaped subcavities.

The housing parts are comprised preferably of a thermoplastic synthetic material, for example, PPS (polyphenyl sulfide). The connection of the housing parts with one another is realized, for example, by friction welding.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 shows an axial section of a housing of a radial compressor;

FIG. 1A shows an axial section of a housing of a radial compressor of FIG. 1 including a schematic depiction of a compressor wheel rotatably supported in the housing;

FIG. 2 shows an illustration of an alternative embodiment of the housing according to FIG. 1;

FIG. 3 shows a further alternative embodiment of the housing according to FIG. 1.

FIG. 4 is an illustration according to FIG. 2 with an annular radial partition for forming two subcavities.

FIG. 5 is an illustration according to FIG. 3 with axial partitions for forming several subcavities.

FIG. 6 is a schematic illustration of subcavities that are formed by the partitions of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a housing 1 that is comprised of three housing parts wherein between the top part 2 and the bottom part 3 a central part 4 is arranged. These housing parts 2, 3, 4 are comprised of a thermoplastic synthetic material, for example, PPS (polyphenyl sulfide). On the top part 2 there are two annular joining or connecting surfaces 5, 6 wherein on the connecting surface 5 an end face 7 of the bottom part 3 and on the connecting surface 6 a contact surface 8 of the central part 4 are resting. The connecting surface 5 and the end face 7 as well as the connecting surface 6 and the contact surface 8 form welding zones, respectively, where the parts are integrally joined or bonded. FIG. 1A shows the radial compressor housing of FIG. 1 including a schematic depiction of a compressor wheel 52 rotatably supported in the housing.

On the top part 2 a curved portion 9 that is open in downward direction is formed that extends in an annular shape and is widening in the circumferential direction. On the radially inwardly positioned end of this curved portion 9 the connecting surface 6 is formed. The contact surface 8 is adjoined by a rounded section 10 that is matched to the shape of the curved portion 9 and is formed on the central part 4. The central part 4 comprises also an axial section 11 with a rounded portion 12 adjoining the radial section 13 to which the rounded section 10 is integrally and monolithically connected.

On the top part 2 an axial section 14 is formed that is aligned with the axial section 11 of the central part 4. The axial sections 11, 14 form an inflow passage 19 wherein between the sections 11 and 14 a spacing exists by means of which a slot 15 is formed that extends in circumferential direction. The axial section 14 of the top part 2 is connected by wall parts 16, 17 with the curved part 9. These wall parts 16, 17 as well as the axial sections 11, 14, rounded portion 12, and radial section 13 delimit an annular cavity 18 that extends about the axial sections 11, 14 that is fluidically connected by the slot 15 with the inflow passage 19 formed by the axial sections 11, 14. As can be seen in FIG. 1, the annular acoustic dampening cavity 18 is arranged between the axial sections 14, 11 and spiral passage 24, with the axial sections 11,14 radially inwardly relative to the annular cavity 18 and the spiral passage 24 arranged radially outwardly from the annular cavity 18.

The bottom part 3 is substantially formed as an annular curved portion 20 that widens in circumferential direction and is provided at its radial external side with an axially upwardly extending sleeve 21 having at its upper end the end face 7. On the inner wall of the sleeve 21 an axial section 22 of the top part 2 is resting so that in this area the housing 11 is of a double-wall configuration. The bottom part 3 is formed at its bottom side for receiving a housing bottom, not illustrated in the drawing, wherein on the bottom housing part 3 radially inwardly oriented projections 23 are provided. As can be seen in the illustration, the curved portion 9 of the top part 2, the rounded section 10 of the central part 4, and the curved portion 20 of the bottom part 3 together form a spiral passage 24. An axis 50 is shown identifying an axial direction relative to housing 1.

FIG. 2 shows the housing 1 in an alternative embodiment wherein the central part 4 is provided with a longer axial section 27 that extends up to the bottom edge of the radially extending wall part 16. On the bottom edge of the wall part 16 a further connecting surface 25 is provided that is abutted by an end face 26 of the section 27; the top part 2 and the central part 4 are integrally joined or bonded at the surfaces 25, 26 as well as at the surfaces 6 and 8. In the cylindrically embodied section 27 a plurality of slotted holes 28 is arranged that, in the illustrated embodiment, are formed as parallel extending slots and fluidically connect the cavity 18 with the inflow passage 19. In other respects, same parts are identified with same reference numerals as in FIG. 1 so that reference is being had to the description of FIG. 1.

In FIG. 3 a further embodiment of the housing 1 is shown that differs from that of FIG. 2 in that in the cylindrically embodied axial section 27 circular openings 29 are arranged by means of which the cavity 18 is fluidically connected with the inflow passage 19. Of course, also other shapes of the openings are possible, for example, shaped as irregular polygons or as regular polygons. In other respects, same parts are identified with same reference numerals as in FIG. 2.

In FIG. 4, an illustration similar to that of FIG. 2 is shown but in contrast thereto in FIG. 4 an annular radial partition 30 is provided in the cavity surrounding the radial section 27 so that in this illustration of the housing 1 an upper subcavity 31 and a lower subcavity 32 are formed. Each one of the subcavities 31, 32 is fluidically connected by slotted holes 28 with the inflow passage 19. In other respects, same parts are identified with same reference numerals as in FIG. 2.

FIG. 5 shows an embodiment variant of FIG. 3 wherein in the cavity surrounding the axial section 27 at least two axially aligned partitions 34 are arranged; in FIG. 5 only one partition 34 is illustrated. These partitions 34 serve for forming several subcavities 33 as indicated schematically in the illustration of FIG. 6. In other respects, same parts are identified with same reference numerals as in FIG. 3.

Separation into several cavities 31, 32 in FIG. 4 as well as 33 in FIGS. 5 and 6 provides for boxing of the volume, i.e., formation of two or several individual volumes. These individual volumes may be of the same size or may be differently sized.

While specific embodiments of the invention have been shown and described in detail to illustrate the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles. 

1. A radial compressor for a turbo charger, comprising: a housing comprising an inflow passage and a spiral passage; a compressor wheel supported rotatably in said housing; wherein said housing is comprised of at least two housing parts between which an acoustic dampening cavity is formed; at least one opening provided in said inflow passage, wherein said at least one opening fluidically connects said cavity with said inflow passage.
 2. The radial compressor according to claim 1, wherein said at least two housing parts include a central housing part and wherein said inflow passage is substantially formed by an axial section of said central housing part.
 3. The radial compressor according to claim 2, wherein said axial section of said central housing part, said at least one opening is a plurality of openings.
 4. The radial compressor according to claim 3, wherein said plurality of openings are slotted holes.
 5. The radial compressor according to claim 4, wherein said slotted holes extend parallel to one another in an axial direction of said inflow passage.
 6. The radial compressor according to claim 5, wherein said plurality of openings are circular or polygonal.
 7. The radial compressor according to claim 2, wherein said cavity is annular and surrounds said axial section of said central housing part.
 8. The radial compressor according to claim 7, comprising an annular radial partition that divides said cavity into an upper subcavity and a lower subcavity each having a separate individual volume.
 9. The radial compressor according to claim 2, comprising three axial partitions that divide said cavity into three ring segment shaped subcavities that surround said axial section of said central housing part.
 10. The radial compressor according to claim 1, wherein said at least two housing parts include a central housing part and a top housing part, wherein said inflow passage is substantially formed by an axial section of said top housing part and an axial section of said central housing part.
 11. The radial compressor according to claim 10, wherein said at least one opening in said inflow passage is formed by a spacing between said axial section of said top housing part and said axial section of said central housing part.
 12. The radial compressor according to claim 11, wherein said spacing forms a slot extending in a circumferential direction of said inflow passage.
 13. The radial compressor according to claim 10, wherein said cavity is annular and surrounds said axial section of said top housing part and said axial section of said central housing part.
 14. The radial compressor according to claim 13, comprising an annular radial partition that divides said cavity into an upper subcavity and a lower subcavity each having a separate individual volume.
 15. The radial compressor according to claim 9, comprising three axial partitions that divide said cavity into three ring segment shaped subcavities that surround said axial section of said top housing part and said axial section of said central housing part.
 16. The radial compressor according to claim 1, comprising a partition that divides said cavity into two or more subcavities.
 17. The radial compressor according to claim 1, comprising at least two axial partitions that divide said cavity into several subcavities.
 18. The radial compressor according to claim 1, wherein said at least two housing parts are comprised of thermoplastic synthetic material. 